Vibrating/ droning sound since new hot water cylinder was installed.

[Johntheo5]

Re the Honeywell zone valves. With the valve de energized, the "manual" lever can be pulled across against a fairly stiff motor resistance and then pushed up and latched almost fully open, this (on Honeywells), does not fire the boiler, its main purpose is to manually open the valves when draining/filling the system. If the valve is then energized the motor will drive the valve very fully open, the lever will fall down out of its latch, the auxiliary end switch in the actuator will then close to fire the boiler, when the valve is de energized then the valve will reclose because its no longer latched in.

Next time the droning is at its worst, ensure both zone valves de energized, then fire up the boiler on heating (rads) only, see does the noise return, if not, manually latch open the HW zone valve and check for noise.

 

[Johntheo5]

When droning noise started, I ran the hot tap, the noise stopped instantly. The longer I ran the hot tap the longer it takes for sound to return. It’s droning continuously this morning, not initially… when it first comes on at 6.20am (timed on the programmer) because it hasn’t been on all night, it initially heats quietly. It’s when the cylinder must be full of hot water, when it’s at its worst. So when the boiler fires up intermittently. The droning starts. It has just droned constantly for 5 minutes more, had a 2 minute rest and then starts again.

Once you run off a few litres of HW then there is no expansion effect even if the cylinder is still being heated so a bit strange that the noise returns with the HW still opened?.
Again, until my dying day, I will never understand why a pressure vessel like a unvented HW Cylinder doesn't have a pressure gauge.

 

[LuLuKD]

No, it wasn’t an open vented.

Arrow on the brass valve body: indicates the intended direction of water flow. The valve must be installed in the correct direction for that model and circuit.
Motorised head: on many Honeywell 2-port valves, the actuator head can be fitted in several permitted orientations, depending on the exact model. It doesn’t generally have to point in the same direction as the arrow.

 

[LuLuKD]

I found another forum, with a guy who had the same cylinder as me installed, with the same annoying aircraft droning sound. Apparently Gledhill cylinders are known for their coil vibration. In this particular instance, the issue was resolved by the plumber adjusting the gate valve.
If I don’t have a gate valve, shouldn’t I have a ABV installed? Like Mister Banks said

 

[Johntheo5]

A ABV normally opens when the (last) zone valve closes to enable the boiler circ pump to overrun and circulate water for a minute or so to cool down the boiler heat exchanger after it shuts down.

This gate valve may have been installed on the cylinder heating coil return and throttled in.

 

[fixitflav]

are you referring to separate manual isolation valves on the HW circuit?

This is a manual valve I was thinking of, looks like it's on the cylinder primary outlet. There might be other valves we can't see.

 

[fixitflav]

When droning noise started, I ran the hot tap, the noise stopped instantly. The longer I ran the hot tap the longer it takes for sound to return. It’s droning continuously this morning, not initially… when it first comes on at 6.20am (timed on the programmer) because it hasn’t been on all night, it initially heats quietly. It’s when the cylinder must be full of hot water, when it’s at its worst. So when the boiler fires up intermittently. The droning starts. It has just droned constantly for 5 minutes more, had a 2 minute rest and then starts again.

That sounds to me like it's reaching HW setpoint, so the HW motorised valve closes, but the pump continues to run.

 

[Johntheo5]

That sounds to me like it's reaching HW setpoint, so the HW motorised valve closes, but the pump continues to run.

That's well worth investigating if the droning only occurs after/when the HW zone valve closes and stops droning when the circ pump finishes its overrun time, assumes HW heating only on.

 

[Justin Passing]

I haven't worked out all the details in the thread, but NB expansion vessels can do it. You would feel it.